Sounds like the Smartboard is running at an odd frequency (not 60hz) like an old CRT computer monitor. You can use the HDX's shutter and dial in the frequency and make the flicker go away.

1st, make sure you have Synchro Scan turned ON in the Menu section. Then, switch on the shutter at the front of the camera under the little cover, click around the settings to select SS and using the 2 buttons near the top side of the camera labeled Synchro Scan, you can fine adjust the shutter rate up or down to sync with the screen and remove the flicker.

Work is a beautiful thing.
Our 900 still is shooting wonderful pictures -- we're shooting mostly 1080p30 -- and using the nano @ 220 Mbps. It's just great.
A fellow 900 user out of Atlanta walked me through some settings on the 900 and what a difference it's made. (We connected through Dan Keaton when I had some questions regarding the nano).
Glad all is well, and thanks again.

I've got a Nano too. But, some clients still want tape - go figure. I've got both covered. The Convergence folks are awesome and they are right here in Colorado by me. I'm on the list to get their new Odeyssey7 OLED monitor.